The subject of this invention is a programmable cylinder lock, namely a lock comprising devices intended to allow the initial codification of the lock or, through a change operation, to modify the former lock codification in order to adjust the lock for being operated by a key different from the key to which the lock was formerly adapted.
This invention also concerns the use keys and the change keys having special characteristics in order to operate this lock. More particularly, the invention concerns improvements to a kind of programmable cylinder lock, which is known from EP 0.226.252 and EP 0.900.310. The documents US 2009/277239 and US 2005/217330 are also of interest.
In a usual cylinder lock, which comprises a stator and a cylindrical rotor mounted inside the stator, rotatable around its own axis and having a keyhole extending along the direction of the axis for insertion of a key, a number of locking pins is mounted in the rotor, movable perpendicularly to the axis on the extension of the keyhole plane, and each locking pin is intended to cooperate with a section of the key, whose codification is represented by the level of a tooth or recess of the key which is situated in the considered key section. The length of each locking pin is such that, when it cooperates with the corresponding section of the correct key, its distal end portion corresponds to the cylindrical rotor surface and does not hinder its rotation, whereby, when all the locking pins are displaced in their respective correct positions by the correct key, the rotor can be rotated for operating the lock. When, on the contrary, one or more locking pins are not in their correct positions, they (or counterpins which may be provided in the stator) extend through the cylindrical rotor surface and hinder the rotation thereof and therefore the operation of the lock. Because the lock codification is represented by the lengths of the locking pins, and is established during the manufacture, the lock can be operated by only one correct key, and it cannot be programmed.
The programmable locks of the kind to which applies the present invention and which are described in the cited documents comprise, within a rotor rotatably mounted inside the stator, instead of locking pins having preestablished lengths, a number of key followers movable along their longitudinal and transversal directions, intended to cooperate with the codification conformations of a key inserted into the rotor keyhole, and locking pins having longitudinal movability which are the blocking members of the lock. The key followers and the locking pins form pairs each comprising a locking pin and a key follower, and the locking pins and key followers are provided with toothings intended to mutually cooperate, in different relative positions, for determining the lock codification. A transversally displaceable stop bar, cooperating with a longitudinal stator groove and having projections suitable for cooperating with recesses of the locking pins, is intended to immobilize the locking pins when the rotor is rotated within the stator and, as a consequence, the stop bar comes out of said groove and engages the locking pins. A transversally displaceable change bar is slidably engaged with the key followers and normally retains the same engaged with the locking pins, but this change bar, when it enters said stator groove, transversally displaces the key followers by disengaging the same from the locking pins, thus allowing the modification of the lock codification by replacing the former key by a new different key.
In a lock of this kind, during the rotation of the rotor for operating the lock, the rotor passes through the change position, and then the key followers are momentarily disengaged from the locking pins. If, though not being desired a change, in this position the key is extracted or displaced, the lock codification is lost or modified. For this reason there are known different protection systems intended to hinder the extraction or the displacement of the key when a change is not required. However, in the change position of the rotor the engagement between the key followers and the locking pins is missing and therefore, even in the presence of such protection systems, the lock codification might be modified or adulterated by rendering the same less precise, by accidental causes, such as clearances, a key wear or other grounds. Therefore, the known protection systems are not entirely effective.